Precision lathes



1956 v. M. Hovls, JR, ETAL 3,264,912

PRECI S ION LATHES Filed Oct. 16, 1964 7 Sheets-Sheet 1 INVENTORS. Vicfor M. How's, Jr. BY Edward E. Palmer ATTORNEY 9, 1966 v. M. HOVIS, JR., ETAL 3,264,912

PRECI SION LATHES 7 Sheets-Sheet 2 Filed 001:. 16, 1964 mm wmzwi E 32 528 7 3 32 uc u 6 2.33:3 *o 5:50 52:00 QE we 239 50 *0 meuum I 62 E5 QM 65 25m INVENTORS. Vicfor M. Hovis, Jr. Edward E. Palmer ATTORNEY Aug. 9, 1966 v. M. HOVIS, JR, ETAL 3,254,912

PRECISION LATHES Filed Oct. 16, 1964 '7 Sheets-Sheet 5 INVENTORS. Vicfor M. Hovis, Jr. BY Edward E. Palmer ATTORNEY.

Aug. 9, 1966 v. M. HOVIS, JR., ETAL 3,254,912

PRECISION LATHES Filed Oct. 16, 1964 7 Sheets-Sheet 4,

FIGURE-4 FIGURE-6 FIGURE-'8 INVENTORS'. Victor M. Hovis, Jr. BY Edward E. Palmer ATTORNEY.

Aug. 9, 1966 v. M. HOVIS, JR.; ETAL 3,264,912

PRECISION LATHES Filed Oct. 16, 1964 7 Sheets-Sheet 5 INVENTORS. Vicfor M. Hovis, Jr. BY Edward E. Palmer ATTORNEY.

g 9, 1966 v. M. HOV|S,JR., ETAL 3,264,912

PRECISION LATHES Filed Oct. 16, 1964 7 Sheets-Sheet 6 I2 FIGURE-IO FIGURE-'7 INVENTORS.

Vicfor M. How's, Jf/

BY Edward E. Pa/mr flrfl/m ATTORNEY.

FIGURE-9 g- 9, 1966 v. M. HOVIS, JR., ETAL I 3,264,912

PRECISION LATHES 7 Sheets-Sheet '7 Filed Oct. 16, 1964 m a m T mmnoE N w a E 0 P mm W H E l M d r r w W .wd V E Y B o:

ATTORNEY.

United States Patent PREClSlUN LATHES Victor M. Hovis, Jr., Kingston, and Edward E. Palmer, Knoxville, Tenn, assignors to the United States of America as represented by the United States Atomic Energy Commission Filed Oct. 16, 1964, Ser. No. 404,529 Claims. (Cl. 82-14) This invention relates to precision lathes and more particularly to a control system for the automatic control of a precision tracer lathe, and is an improvement over the prior copending application of Hovis, S.N. 340,834.

7 The duplicator or tracer lathe employs the X-Y coordinate system of positioning and operates on the general principle of a command stylus tracing a fixed contoured template and generating a signal. The signal is transmitted to the controls of a hydraulic system driving a 45 angle slide on the lathe which supports the cutting tool. The 45 angle slide carries a stylus adjustment compound slide. Successive cuts on the workpiece are made by retracting the command stylus which results in advancing the machining tool with respect to the workpiece. This mode of operation possesses several error-generating features. One is the inability of the presently known means for advancing machining tools via a compound slide to move the tool in increments of a few microinches. This error results primarily from errors in lead screws, slip-stick friction, and the like. A further error involved in the conventional tracer lathe arises from the presence of certain cumulative inaccuracies detailed hereinafter.

Surfaces of revolution are produced by combining one rotary motion with three reciprocatory motions. The reciprocatory motions are superimposed upon each other in a stacked array that culminates in reduced accuracy in the guidance of the cutting tool and stylus. This results from the fact that conventional linear guide systems do not maintain a high degree of precision under changing conditions of load and usage.

The manual alignment of a contoured template with the axis of rotation of a workpiece cannot be readily attained with a high degree of precision. In conventional XY lathes, the template is aligned with the longitudinal guide ways which in turn are aligned with the axis of rotation. Cumulative errors are thus introduced which are very diflicult to detect and eliminate.

The angle of approach between the workpiece and machining tool and between the template and the stylus is fixed at 45 to the longitudinal axis for conventional duplicator lathes. Tracing errors are introduced that are a function of the angle between the tool and work surfaces, stylus and template surfaces, and between the center line axes of the tool and stylus.

Applicants with a knowledge of these problems of the prior art have for an object of their invention the provision of a tracer lathe capable of machining workpieces to dimensional tolerances in the 50 microinch range.

Applicants have as another object of their invention the provision of a precision tracer lathe wherein the cut-ting operation is carried out by a reciprocating cutting tool.

Applicants have as another object of their invention the provision of a precision tracer lathe which may be quickly and easily adjusted to precisely align a template, tracing stylus and a machining tool.

Applicants have as another object of their invention the provision of a precision tracer lathe wherein successive cuts are selected by moving the template with respect to the workpiece rather than moving the stylus relative to the machining tool to increase the precision of the cut.

Applicants have as another object of their invention the provision of a precision lathe having a tracer which imparts reduced deformation and wear to a template and substantially overcomes the cosine effect.

Applicants have as a further object of their invention the provision of a tracer lathe having a tracer capable of rapidly detecting minute deviations in a template contour and instantaneously converting them into a magnified control electric signal for more precise conformity of the cutting tool path to the contour of the template.

Applicants have as a still further object of their invention the provision of a precision tracer lathe having a positioning device for a template wherein precise, minute and reproducible positioning movements maybe accomplished.

Applicants have as a still further object of their invention the provision of a precision tracer lathe capable of producing surfaces of revolution by the combination of two rotary motions and one reciprocatory motion.

Other objects and advantages of our invention will appear from the following specification and accompanying drawings and the novel features thereof will be particularly pointed out in the annexed claims.

In the drawings, FIG. 1 is a side elevation, partly in section, of our improved precision tracer lathe. FIGS. 2A and 2B are schematic representations of the error created by misalignment of a cutting tool and its command stylus. FIG. 3 is a schematic of the hydraulic slide for actuating the stylus and tool. FIG. 4 is a sectional detail of the improved stylus or tracer element used in our precision lathe. FIG. 5 is a fragment-a1 detail in perspective of the template positioning device for our improved tracer lathe. FIG. 6 is a front elevation of our improved tracer element. FIG. 7 is a side elevation of our kinematic slide assembly. FIG. 8 is a sectional elevation of our improved rotary table and drive. FIG. 9 is an enlarged end view of the Dexter bearing slide assembly. FIG. 10 is a plan view of the kinematic slide assembly. FIG. 11 is a cross sectional view of the kinematic slide arrangement taken along the line 11--11 of FIG. 10. FIG. 12 is a cross section of the kinematic slide assembly taken along the line 12-12 of FIG. 10.

Referring to the drawings in detail, FIG. 1 is a precision tracer lathe with a machining tolerance capability of the order of microinches. It includes a fluid supported rotary spindle 43, a hydraulically supported slide or boring bar 19 which carries a tool 20, a vacuum chuck 42 to precisely mount a workpiece, a precision template positioning and mounting device 41, a sensitive light-touch tracer or stylus 38, a conventional tracer lathe base and superstructure -1, a rotary table 10 which rotates the cutting tool 20 during the cutting operation, and a displaceable shaft 70 for coupling hydraulic motor 12 through speed reducer 16 and coupling 13 to the rotary table 10 to drive it.

The conventional tracer lathe has a base 1 and a bed 2 upon which are mounted ways 5 over which travels a longitudinal carriage 6, herein called the X slide and may be operated by the usual handwheel 46. Upon carriage 6 is mounted a Y slide 7 which also may be operated by handwheel 9 to move it transversely of the bed 2. The X-Y slides are, of course, conventional in the art. However, mounted on the Y slide 7 so as to be interposed between it and the hydraulically supported slide 19 is a rotary table 10. The rotary table 10 has afiixed to the upper rotating part a spacer plate 11 which is part of the housing 18 and through which screws 52 pass to join the plate to the table 10.

The rotary table of FIG. 8 is of conventional construction and is integral to shaft 101 and supported in bearing 105. It carries a gear 102 which meshes with a worm 103 on shaft 104. Rotation of shaft 104 acts through the worm 103 and gear 102 to rotate the table 10.

As shown in FIG. 1;, shaft 104 is driven by a hydraulic motor 12 such as a Vickers Constant displacement piston motor shown in Patent Nos. 2,250,515; 2,313,407; 2,365, 067; and 2,404,309. Motor 12 couples to shaft 104 through a speed reducer 16 such as that made by Boston 3 Gear Company, Patent No. 2,868,031 and an extensible shaft 70 comprised of a pair of universal connections 14, joined to a square shank telescoped within a socket or alternatively to a splined shaft 17, as desired. This permits relative movement between speed reducer 16 and parts of rotary table 10.

The third slide mounted on rotary table 10 is hydraulically suspended and operated, and is described in detail in the prior copending application of Hovis, supra. As shown in FIG. 3, slide 19 forms a portion of a double-acting piston and housing 18 forms the cylinder. The cross section of slide 19 is non-circular, preferably rectangular, and so is the passage in the housing 18 that accommodates the slide. The operation of the piston is controlled by the tracer 38 acting through preamplifier 53 and amplifier 54 to operate valve 55 and cause the slide 19 to reciprocate in accordance with the pattern on the template 40.

Slide 19 is comprised of two end sections and a reduced intermediate section 56, cylindrical in cross section. Encircling and spaced from section 56 of slide 19 with a slight radial clearance of the order of .003 inch or .004 inch to provide satisfactory restriction of flow and partially embedded within the interior of housing 18, is a rigid annular labyrinth seal 57 constructed of any suitable rigid material. Seal 57 divides the space defined by housing 18 and the reduced section 56 of the slide 19 into two equal chambers 58, 59. The portions of slide 19 on either side of reduced portion 56 are no less than .002 inch on a side smaller than the interior opening of the housing 18.

Housing 18 is provided with at least two sets of four pockets each for each side of the slide 19. Pockets 60 are preferably rectangular depressions although they may have any suitable configuration. They are formed in the interior walls of the housing 18 and serve to receive and distribute hydraulic fluid. Pump 61 feeds from storage tank 62 through a pressure relief valve 63 to a series of pipes, each of which has an orifice 64 that supplies hydraulic fluid to a pocket 60 under conditions of selected constant pressure, flow and temperature. The orifices 64 are interposed in the individual lines leading to the pockets 60 to produce a pressure drop. As oil flow in the system changes, the pressure drop across the orifice changes so that the transverse force applied to the slide 19 varies. The orifice adjusts the pressure applied in response to oil flow. Pump 61 also supplies hydraulic fluid to the aforesaid servo valve 55 via a line 65. Hydraulic fluid lines 66, 67 afford hydraulic connection between annular chambers 58, 59, respectively, and said valve 55. The hydraulic fluid pressure experienced by pockets 60 and valve 55 are independent of each other. Catch basins 68, 69 are provided to receive out-flowing hydraulic fluid from which basins the fluid may be filtered and recirculated to the pump 61 through tank 62.

The cutting tool 20 of FIG. 1 may take any suitable conventional form and is mounted in, and carried by, one extremity of slide 19. It is preferably held in place by set screws (not shown) or any conventional clamp.

To the tool-carrying end of boring bar 19 of FIG. 1 a mount 21 is joined by bolts 71 and bolted likewise to a structural member 22 suspended horizontally and above boring bar 19 and the housing 18. Structural member 22 is essentially the same length as boring bar 19. The outboard end of member 22 is provided with a support member 23 which depends from said outboard end to rest on that end of boring bar 19 which is directly beneath. Side guides 24 (only one shown) restrain lateral movement of support member 23 without inhibiting longitudinal sliding of support member 23 as structural member 22 expands or contracts in the longitudinal direction, in response to temperature changes. This feature is included to provide maximum support and rigidity to minimize errors caused by the different degrees of longitudinal expansion of boring bar 19 and structural member 22, while precluding vertical displacement caused by bowing due to the different degrees of expansion of the boring bar 19 and structural member 22.

Structural member 22 extends upwardly and longitudinally forward toward the headstock of the lathe to support a template tracer system in a cantilevered fashion vertically over machining tool 20. A novel positioning device serves to effect joinder between structural member 22 and said tracing system. This positioning device comprises a base 25, secured to said member 22, a bottom metal plate 26 rigidly secured to said base 25, a pad of elastically deformable material 27, preferably adiprene, bonded between said bottom plate 26 and a second plate 28. Said second plate 28 is provided with adjustment means 29 and 30 capable of imparting sufiicient shear stress to said second plate 28, which will, when transmitted to pad 27, cause elastic deformation of said pad, hence movement thereof, and positioning of said second plate 28. The position limits are determined by the maximum elastic deformation which pad 27 can withstand. The template tracing system mounted on said second plate 28 is thereby positioned by elastic deformation of pad 27 relative to plate 26. I

Mounted on plate 28 is the template tracing system of FIGS. 4 and 6 which comprise a body member 31 of basically L shape with a Linear Variable Diflerential Transducer (LVDT) 33 embedded in one leg 32 of said body member 31, the sensing head 34 of said LVDT 33 protruding to the inside of said body member 31 where it operatively contacts an upstanding leg 35 of a lever arm 36 hinged to the end of leg 32 of said body member. The lever arm 36 comprises an upwardly projecting leg 35 and a depending leg 37 joined in offset relation through a block 79. The depending leg 37 is joined to block 79 through screws 39, shown in FIG. 6, and the upstanding leg 35 is joined to block 79 through screws 80. The depending leg 37 serves as a mounting means for a stylus 38 having a radial tip 73 for contacting the templates 40, of FIG. 1. The hinge for pivotally attaching lever arm 36 to leg 32 consists of a flat wide strip 72 of metal such as spring steel and as such allows only unidirectional movement of lever arm 36 with respect to leg 32. The hinge 72 is secured to leg 32 by block 77 through which screws 78 pass and thread into leg 32 and hinge 72 is sandwiched between them. It is similarly attached to lever arm 36, being sandwiched between block 79 and depending leg 37 and being joined thereto through screws 39.

Lever arm 36 has three legs, i.e., a hinge joining leg 79, a stylus leg 37 and a transducer leg 35. The hinge connection of base arm 32 and lever arm 36 is such as to cause the transducer leg 35 to be substantially parallel to and in juxtaposition to the innermost side of arm 32. The flat plate configuration of hinge 72 allows lever arm 36 only one degree of freedom of movement. It is important that lever arm 36 be so restricted. Any movement of leg 35 will result in movement of leg 37, and hinge 72 will be placed in momental stress by movement of lever arm 36 with respect to arm 32.

Through appropriate adjustment of set screw 74 rotation of stylus tip 73 through an angle of up to 180 may be affected. Leg 35 extends upward to operatively contact LVDT 33. The sensing head 34 of the LVDT 33 is contacted by a set screw threaded into an opening in leg 35 and in axial alignment with LVDT 33. The construction of the LVDT is conventional but is described in detail in the Hovis copending application, supra. LVDT 33 is adjustably mounted in leg 32 by means of an encompassing brass sleeve 75 and a set screw 76 threaded into the wall of leg 32 to engage sleeve 75 which locks LVDT 33 in its adjusted position.

In the preferred embodiment, the verticle distance from tip 73 to hinge 72 is 1 unit, while the vertical distance from hinge 72 to the longitudinal axis of set screw 100 is 2 units. This provides a mechanical advantage such that any longitudinal movement of tip 73 will result in twice that movement at set screw 100. Consequently,

the signal generated by LVDT 33 has twice the signal amplitude as compared with the signal which would be generated if the LVDT were in direct contact with the pattern at tip 73.

Since tip 73 is caused to trace a contoured pattern making point contact with the pattern, it is important that tip 73 maintains a fixed relationship to the contour of the pattern during one or more tracing operations, in order to very precisely portray the pattern traced. The inventors choice of a flat plate hinge for mounting tip 73 gives a fixed spatial relation to a template.

LVDT 33 possesses a spring-loaded sensing head 34. As may be seen in FIG. 4, sensing head 34 makes physical contact with set screw 100. Lever arm 36 through its pivotal movement will develop a torque at the hinge 72. If LVDT 33 is moved with respect to its mount so as to cause sensing head 34 to exert a force upon lever arm 36, there will be an opposing force created at the hinge 72. By moving LVDT 33 and set screw 100 these opposing forces may be chosen so that the spring holding sensing head 34 in the protruded position never exceeds its spring constant, hence operates as a rigid part of LVDT 33. Thus, a force equal to or less than said spring constant can be pre-set into hinge 72 to operate in opposition to said spring. The effect is to reduce the force necessary to overcome said spring constant and create movement of sensing head 34 with respect to its housing. This movement of the sensing head 34 with respect to the housing of LVDT 33 results in generation of a signal.

The torque force developed by hinge 72 is partially determined by the thickness of the hinge. By substituting a thicker or thinner hinge, a change in assist force can be created without atfecting the desired increase in sensitivity.

Referring to FIG. 1, the template 4t) engaged by the stylus is rigidly secured to a multi-unit positioning assembly 41 of FIG. 5 which has two pairs of conventional Dexter hearings or kinematic slide unit assemblies 81 for X and Y axis translation. The X-Y axis slides are shown in FIGS. 7, 11 and 12 for rough positioning and employ plates 103, 106 and 110 mounted on roller bearings 111 mounted in grooves 12 and constrained by appropriate guides 113. The kinematic slide assembly 31 is rigidly mounted on base plate 82. Base plate 82 is then in turn mounted on invar 83 through a layer of elastic material such as adiprene 107 to form a sandwich. The adiprene or other elastomer is bonded to the opposed faces of the invar plate 83 and base 82. The movements of the slides with respect to the base plate 82 are accomplished by the adjustment of micrometers 47 mounted in bearings 84 on base plate 82 and joined to their respective slides of assembly 31 for X and Y movement thereof.

The operation of the template positioning assembly 41, shown in FIGS. 5, 7, 9 and 10, is as follows:

The template is mounted upon plate 103 and aligned with the longitudinal axis of the lathe by abutting said template 40 of FIG. 1 against the alignment pins 45. The template is then locked in position by toe clamps (not shown). As can be seen in FIG. 10, tension springs 104 and 105 are provided between the plates 103 and 106, their purpose being to keep the sides of the floating plates in constant contact with the micrometers 47, 47.

Once this template mount is aligned to the longitudinal axis of the machine, any template may be set up without having to realign it. Secondly, depending on whether the template being used is an inside or outside one, the top plate 103' will carry the template in either an X or Y direction and maintain proper alignment with the axis of the machine. This results in a minimum setup and alignment time for templates.

In its operation course adjustments of the positions of the template are made by movement of the micrometers 47. Then fine adjustments of the order of microinches are accomplished by rotating handwheel 48 to thread it onto stud to compress the belleville springs 92. As shown in FIG. 5, the compression forces draw studs 85 through bearing blocks 108 mounted on plate 82 and act through yokes 94 to displace base plate 82 relative to invar plate 83, placing the adiprene 107 in elastic shear. Pins 109 mounted on plate 82 project through openings in yokes 94, 94 and serve as a couple to guide them. To adjust in the opposite direction, wheel 48 is threaded off of stud 85 to release the pressures of the belleville springs 92 so that the adiprene layer will restore itself and displace base plate 82 to the new adjusted position. Wheels 48 function as verniers, translating sub stantial radial movements into slight linear movements of base plate 82.

To determine the degree of movement of the metal plate 82 produced as hereinbefore described, we have provided two pairs of LVDTs 9t), positioned on opposite ends of yoke members 94, as shown in FIG. 5. Electrical leads pass from each LVDT to appropriate meters 93 for indicating the signals generated by the LVDTs resulting from movement of yoke members 94.

As will be apparent from FIG. 5, yoke 94 and its associated elements are provided to move base plate 82 along a single line of movement for fine adjustments. Since positioning movements may not all be along this single line, applicants have provided an additional yoke 94 located 90 from yoke 94. The second yoke and its operating arrangement may be a duplicate of the first yoke system as described above.

As shown in FIG. 1, the lathe is provided with a rotating spindle 43 driven through a conventional Brown and Sharpe hydraulic head shaft unit 44 by an AC. motor 49 of conventional type. The spindle 43 mounts a vacuum chuck 42 with the vacuum pressure being applied to the chuck through chamber 51). The vacuum chuck may take any suitable form. Motor 49 which rotates chuck 42 through spindle 43 and head shaft unit 44 is mounted on a dovetail slide carried by base 1 and clamped in place by studs 95, 95.

It will be noted at this point that all the elements 51, 22, 19, 10 and 7 reside on slide 6 and movable therewith. When an operator desires to place a workpiece in the chuck or remove one, he can, by moving slide 6 rearward, move the compound slide 7, rotary table 10, boring bar '19, and template tracer arrangement 51 as a unit, and never disturb their relative positioning. This feature affords convenience but, more importantly, permits an exchange of workpiece without disturbing the vertical align ment of tool 29 and radial tip 73, FIG. 4. With exact vertical alignment of cutting tool 20 and stylus radial tip '73, the cutting tool path will be identical to the template contour desired. Vertical misalignment of cutting tool 20 and stylus radial tip 73 will cause the cutting tool path to deviate from the desired template contour. For example, misalignment of cutting tool 20 and stylus radial tip 73 in the manner shown in plane view FIG. 2A will result in the difference between the template contour and the cutting tool path shown in FIG. 2B. It is essential that these two elements be precisely vertically aligned or the contour cut by the tool will not be identical to the contour traced by the stylus. This concept of error is depicted in FIGS. 2A and 2B.

In using our improved precision lathe, the sequence of operations is preferably carried out as follows:

(a) a hemispherical workpiece is positioned in the vacuum :chuck 42.

(l) Align I.D. chuck 42 shown in FIG. 1 to the spindle 43.

(2) Move template axially until an I.D. chuck electrojet reference reading is established to the special reference surface of template. Move template cross-axially until pole of template is approximately positioned above pole of part.

(3) Align part in chuck and observe reading of chuck electro-jet. Comparison of this reading with the previous reading will establish relationship of axial position of template to the polar height of the part.

(4) Correct electro-jet template position readings so that template position can be established to give final part polar height.

(5) Measure workpiece diameter with inside micrometers.

(6) Move template until tool touches part cross-axially and record template mount micrometer readings.

(7) Machine part until diameter is within a .005 inch of final dimension, working from inside micro-reading and polar height with .001 inch of LVDT reading.

(8) Set gage block standard and set LVDT diameter gage.

(9) Measure workpiece diameter with gage and set LVDT to template mount to measure cross axial movement.

(10) Machine workpiece until both axial and crossaxial readings indicate final desired part size.

(b) Then a template is secured in position. Posts 45, FIG. 1, represent known positions when adjustments 47, 48 and their companion adjustment (not shown) are set at zero. There :are two sets of holes on plate 103 (FIG. 7) (one set for ID. and one set for 0D. templates) into which posts 45 may be positioned. Thus, to position template 40 grossly, the operator need only choose the proper set of holes for posts 45 and abut template 40 against said posts, clamping it in position.

(c) Then the radial tip 73 of the tracing stylus is aligned directly vertically over the tip of the cutting tool by means of a tool setting device (not shown) and manipulation of adjustments 29 and 30.

(d) The slide 6 is manually advanced by means of handwheel 46, until stylus tip 73, FIG. 4, contacts template 40. The hydraulic control system of boring bar 19 is now actuated and responds immediately upon contact of stylus tip 73 and template 40 to actuate the hydraulic piston 56 of FIG. 3 and properly position boring bar 19 and its cutting tool 20.

(e) Hydraulic system is actuated to pressurize oil bearings of spindle. (Note: Chuck will not rotate until spindle bearing pressure actuates electrical interlock to motor 49.)

(f) The motor 49 is then actuated to rotate chuck 42.

(g) The hydraulic motor 12 is also actuated to cause rotary table 10 to carry boring bar 19, hence tool 20, through an arcuate path thereby performing a cut on the workpiece.

(h) The template 40 is withdrawn from stylus 38 by means of adjustments 47 (and like others not shown). Adjustments, .0001 to .001 thousandths may be made by using micrometers 47 on the kinematic slide assembly 41. Micro adjustments, 5 to 50 microinches, are made by adjusting Wheels 48 of the elastic deformation positioner. Positioning for roughing lcuts may be accomplished through the use of the kinematic slide assembly. Positioning for finishing cuts should be through the micropositioning system.

(i) Step (g) is repeated again and again until the operation is completed.

Having thus described our invention, we claim:

*1. A precision tracer lathe comprising a body, a rotating spindle mounted on the body and having a work mounting chuck thereon, a rotating table mounted on the body, a floating slide hydraulically mounted by the table for mounting a cutting tool, a scanner mounted on the slide for scanning a pattern to produce signals, means responsive to the signals from the scanner for actuating the slide to bring the tool into contact with the workpiece and produce a cut that conforms to a pattern.

2. A precision tracer lathe comprising a frame, a rotary table mounted on the frame for oscillatory movement during operation, an extendable slide hydraulically mounted on the table, a spindle on the frame for continuous rotation, a workpiece mounted to rotate with the spindle, a cutting tool carried by the slide for engagement with the workpiece, a pattern mounted on the frame, a scanner mounted on the slide for engagement with the pattern for producing signals as the rotary table oscillates, and means responsive to the signal from the scanner for actuating the slide to control the cut of the tool on the workpiece.

3. A precision tracer lathe comprising a frame, a rotating spindle for mounting a workpiece, a compound slide mounted on the frame for longitudinal and transverse movement, a notary table mounted on the slide, a power drive for rotating the table during operation, a slide mounted on the rotary table and carrying a tool movable in an arcuate path for engagement with the workpiece carried by the spindle, a stationary pattern mounted on the frame, a scanner carried by said last named slide and movable therewith as the table is rotated to scan the pattern and produce signals, and a circuit coupled to the scanner and responsive to signals therefrom for actuating the slide to move the tool toward and away from the workpiece to control the cut.

4. A precision tracer lathe comprising an elongated frame, a spindle rotatably mounted on the frame for supporting a workpiece, a rotary table adjustably mounted on the frame, a hydraulically supported and operated slide for mounting a cutting tool mounted on said table, a stationary pattern mounted on the frame, a scanner carried by the slide for scanning the pattern, a power drive for rotating the rotary table during the operation of the cutting tool, and means responsive to the movements of the scanner over the pattern to lacuate the hydraulic slide and bring the tool into cutting relation with the-workpiece to control the cut thereof in accordance with the pattern.

5. A precision tracer lathe comprising an elongated frame, a spindle rotatably mounted on the frame for supporting a workpiece, a rotary .table adjustably mounted on the frame, a hydraulically mounted and operated slide for mounting a cutting tool, a stationary pattern mounted on the frame, a scanner carried by the slide for scanning the pattern, and a circuit coupled to the scanner and responsive to signals therefrom for actuating the hydraulic slide toward and away from the workpiece as it is oscillated by the rotary table to cause the cutting tool to machine the workpiece in accordance with the pattern.

References Cited by the Examiner UNITED STATES PATENTS 2,739,495 3/1956 Johnson 8214 3,122,970 3/1964 Roades 90-62 3,139,003 6/1964 Magor -62 3,146,646 9/1964 Mucklenbeck et al. 82-14 3,148,590 9/1964 Bancroft et a1. 9062 3,176,552 4/1965 Weaver 8214 55 WILLIAM W. DYER, JR., Primary Examiner.

G. A. DOST, Assistant Examiner. 

1. A PRECISION TRACER LATHE COMPRISING A BODY, A ROTATING SPINDLE MOUNTED ON THE BODY AND HAVING A WORK MOUNTING CHUCK THEREON, A ROTATING TABLE MOUNTED ON THE BODY, A FLOATING SLIDE HYDRAULICALLY MOUNTED BY THE TABLE FOR MOUNTING A CUTTING TOOL, A SCANNER MOUNTED ON THE SLIDE FOR SCANNING A PATTERN TO PRODUCE SIGNALS, MEANS RESPONSIVE TO THE SIGNALS FROM THE SCANNER FOR ACTUATING THE SLIDE TO BRING THE TOOL INTO CONTACT WITH THE WORKPIECE AND PRODUCE A CUT THAT CONFORMS TO A PATTERN. 